Increase in plasma growth hormone after resistance training under hypoxic conditions

The purpose of this study was to clarify whether plasma concentrations of GH and lactate (La) are concurrently elevated by resistance training under 15.4 % of hypoxic conditions. Six athletes (age, 21.6 ｱ 1.0 y; height, 175.6 ｱ 5.6 cm; weight, 70.4 ｱ 16.3 kg; means ｱ SD) provided written, informed consent to participate in this study. Seated participants (n = 6) performed 3 sets of 10 repetitions each of bilateral knee extensions at an intensity of 60 % 1Repetition Maximum (RM) at 2 min intervals using an isotonic leg extension machine under normoxic and hypoxic conditions. Plasma concentrations of growth hormone (GH) lactate (La) were measured before and after the training. Concentrations of GH significantly increased at 0 min before and 0 min after exercise under hypoxic conditions (p < 0.05 Wilcoxon signed rank test). The concentration of La tended to be higher after exercise under hypoxic, than normoxic conditions but the difference was not significant. The overall rating of perceived exertion (RPE) did not significantly differ between normoxic and hypoxic conditions. Resistance training under 15.4 % hypoxic conditions have stimulated the secretion of GH than normoxic conditions.